We cloned an entire encoding sequence of beta-adrenergic receptor kinase 1 (beta ARK1) cDNA from the hearts of Syrian hamsters through reverse transcription and subsequent polymerase chain reaction. The cloned cDNA contained 2067 nucleotides coding 689 amino acids. The sequence had 95% homology to rat beta ARK1 and 90% homology to human homologue. Cardiomyopathic Syrian hamster, BIO53.58, has been used as a model animal of congestive heart failure. M-mode echocardiography confirmed that left ventricular contractility of 20-week-old BIO53.58 was markedly reduced. The expression of beta ARK1 mRNA in the hearts of BIO53.58 was significantly increased compared to control hamsters, F1b, suggesting that the enhanced beta ARK1 expression is acting as a negative feedback mechanism in order to maintain intracellular homeostasis against accelerated stimulation by catecholamines via phosphorylation of beta-adrenergic receptor.